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upper face brace
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=21453		 Page 1 of 1
Author:  jncllc [ Fri Mar 13, 2009 5:18 pm ]
Post subject:  upper face brace
Somehow I glued my upper face brace ( the one with the hole for the truss rod wrench in it) with the grain running horizonal instead of vertical. Anyone know if this a big problem and should I plane it off and do it again. Thanks, John oops_sign
Author:  Rod True [ Fri Mar 13, 2009 5:21 pm ]
Post subject:  Re: upper face brace
Hi John, welcome to the OLF.

If it were mine, I'd shave it off and re-do it. But I'm rather anal about those types of things.

What are you doing for a neck block? Are you using an extension of some sort? If so, I'd say you'll be fine. If not, I'd say re-do it.

Either that or you can add a second one on the inside of this first one, where the Popsicle stick brace usually goes.
Author:  Steve Saville [ Fri Mar 13, 2009 6:22 pm ]
Post subject:  Re: upper face brace
Generally speaking, there isn't that much difference in strength. It should be OK. That's easy for me to say, I share no risk of having to fix the completed instrument. In about 5-10 minutes, you could have that brace replaced. Braces are pretty cheap too.
Author:  jncllc [ Fri Mar 13, 2009 9:46 pm ]
Post subject:  Re: upper face brace
The popcicle brace is already on. I was carving braces when I noticed this one was shaving different. got to looking and the grain on top looked flat sawn.This is my 1st guitar from an lmi semi serviced kit. Its a drednought and I'm useing their brace pattern.I'm useing a standard mohagany neckblock although I thought about a maple one since the neck will be a flamed maple to match the back & sides. I'm not too familiar with a neckblock extension but wood be interested in learning about it. Thanks, John
Author:  jfmckenna [ Fri Mar 13, 2009 9:58 pm ]
Post subject:  Re: upper face brace
IMO don't worry about it. Look at the bright side, the nicely flat sawn base of the brace glues better to the top then it would quartered.
Author:  Stephen Boone [ Fri Mar 13, 2009 10:00 pm ]
Post subject:  Re: upper face brace
I would re-do it as well. If I can't do any thing about something then I don't lose sleep over it but if it is in my power to fix something then I do my best.
Author:  Terence Kennedy [ Fri Mar 13, 2009 10:29 pm ]
Post subject:  Re: upper face brace
That's really an important brace. I'd re-do it. Or you might be able to inlay a carbon bar as below to strengthen it. Probably would just be easier to re-do it.
Terry

Image

Image
Author:  Hank Mauel [ Fri Mar 13, 2009 11:14 pm ]
Post subject:  Re: upper face brace
jncllc wrote:
The popcicle brace is already on. I was carving braces when I noticed this one was shaving different. got to looking and the grain on top looked flat sawn.This is my 1st guitar from an lmi semi serviced kit. Its a drednought and I'm useing their brace pattern.I'm useing a standard mohagany neckblock although I thought about a maple one since the neck will be a flamed maple to match the back & sides. I'm not too familiar with a neckblock extension but wood be interested in learning about it. Thanks, John



My neck block w/extension photo summary was in the "Jigs, Tools and Techniques" section of the forum, but it does not seem to be accessible anymore.
Here is a photo of one in place, awaiting the back to be glued on. And if you need another brace I'll send you a piece of sitka with the correct grain orientation.
Author:  meddlingfool [ Sat Mar 14, 2009 4:17 am ]
Post subject:  Re: upper face brace
I'd redo it as well, not worth the risk of future problems.
Author:  jncllc [ Sat Mar 14, 2009 6:59 am ]
Post subject:  Re: upper face brace
Ok, [uncle] I'll redo it. I still have plenty of wood left. I was making it a little taller than the plans showed because it was only 1/2"x1/2" and it seemed drilling a 3/8" hole in it would be a little much thats when I got screwed up on my orientation. I made it 5/8" tall that sound ok? If you use an extension do you leave off the popcicle brace?Also do you need a longer trussrod?
Author:  Andy Birko [ Sat Mar 14, 2009 7:07 am ]
Post subject:  Re: upper face brace
At the risk of starting an inexperienced noob vs. expert smack-down, what exactly could go wrong with having the brace flat sawn vs. 1/4'd?

The data shows that strength wise, 1/4'd and flatsawn spruce usually don't have a stiffnes difference and when there is (depending on density IIRC) flatsawn spruce is stiffer than 1/4'd.

I would think that split resistance would be improved but to be honest, I don't know which orientation splits easiest. runout is certainly easier to see.

Finally, the expansion would be a touch higher than with traditional bracing but c'mon, we're talking about a 1/4" total width.

I can't bring myself to use non 1/4'd wood when bracing but every fiber of my brain says there's no good reason not to. If I accidentally did so, I think I'd keep it there for the reasons listed above.

Other than tradition & just plain fear, does anyone have any good reasons why not to stick with the flat sawn brace?
Author:  Laurent Brondel [ Sat Mar 14, 2009 7:28 am ]
Post subject:  Re: upper face brace
Flatsawn is fine, it actually may be stronger in this application. Bouchet used a flat sawn UTB on his guitars. Lutes were (are) routinely constructed with flat sawn ladder braces. The only difference is how it would split in case of shock. I wouldn't sweat it.
Author:  Alan Carruth [ Sat Mar 14, 2009 1:10 pm ]
Post subject:  Re: upper face brace
I've always felt that a quartered surface glues a little better, but some folks tihnk it's the other way. From that I'd conclude that there's probably not a lot of difference. Otherwise, as has been said, the stiffness and so on should not be different, and, as Laurent pointed out, there's ample precedent for using flat cut bracing. I think we tend to obsess about the wrong things, sometimes.
Author:  Alexandru Marian [ Sat Mar 14, 2009 1:36 pm ]
Post subject:  Re: upper face brace
Acorrding to Romanillos, Torres often installed transverses this way, and sometimes rift sawn. I also saw such a brace in a modern guitar.
Author:  Hank Mauel [ Sun Mar 15, 2009 12:45 pm ]
Post subject:  Re: upper face brace
jncllc wrote:
Ok, [uncle] I'll redo it. I still have plenty of wood left. I was making it a little taller than the plans showed because it was only 1/2"x1/2" and it seemed drilling a 3/8" hole in it would be a little much thats when I got screwed up on my orientation. I made it 5/8" tall that sound ok? If you use an extension do you leave off the popcicle brace?Also do you need a longer trussrod?


Popsicle brace is omitted.
Regular length truss rod. You access it as usual from a sound hole direction. The hex wrench is guided via the curved slot routed in the extension.

5/8" tall is fine, but you can make it thinner...say 1/4 to 3/8" wide and still have more than enough strength while reducing mass. Do you really need a 3/8" diameter hole? What is the truss rod wrench size? Perhaps a 5/16 or even a 1/4" access hole will be adequate.
Author:  David Newton [ Sun Mar 15, 2009 2:20 pm ]
Post subject:  Re: upper face brace
I'd leave as well. I flex my spruces by hand as I'm choosing them and I think most square section spruce varies very little in stiffness, flat vs vertical. And if you did leave it larger than what was designed for that brace (so typical of an early build, the tendency to over build) you will be fine.

But, as others have said, it is about a 30 minute turnaround.
Author:  LiquidGabe [ Sun Mar 15, 2009 3:32 pm ]
Post subject:  Re: upper face brace
I'm a bit surprised by this thread. I have always read that nothing short of perfect quarter is acceptable for braces. Many, if not most going so far as to split braces rather than saw them....

So all the stock I have that is 10-15 deg. off quarter, that I have been truing meticulously should not really concern me?
Author:  Alan Carruth [ Sun Mar 15, 2009 5:20 pm ]
Post subject:  Re: upper face brace
LiquidGabe wrote:
"I'm a bit surprised by this thread. I have always read that nothing short of perfect quarter is acceptable for braces. Many, if not most going so far as to split braces rather than saw them...."

Splitting out brace stock is not done to ensure perfect quartered grain orientation. Rather, it's to minimise runnout and to make sure that the grain in the braces is straight. However, since spruce splits best along the radius of the tree, this does result in a quartered face on the brace.

My feeling is that a lot depends on which brace you're talking about. The X braces, and the 'tone bars' in the lower bout, really do need to be as light and stiff and uniform as you can make them, so it's best to use split stock for these. The UTB is mostly structural, and weight is not as much of a consideration, so if you want to saw out a brace that's off quarter, and feel you need to beef it up a little to make it strong enough, go for it. Weight in the upper bout is not as much of an issue as it in the the lower bout.
Author:  jncllc [ Sun Mar 15, 2009 10:34 pm ]
Post subject:  Re: upper face brace
Hank, 3/8" is the the size Robbie O'Brian made his. I could probably go as small as 1/4". Also he says he makes his a little taller than the plans show. I haven't taken it off yet, I may leave it and just make it a little thinner.
Author:  CraigSz [ Mon Mar 16, 2009 5:51 am ]
Post subject:  Re: upper face brace
Please forgive my hijacking your thread John but your question got the old brain ticking over and thinking about 1/4 sawn brace stock laid on it's side with the grain running parallel to that of the soundboard. Maybe my logic is totally off track but wouldn't the X and tone braces resist the load of the strings better with this orientation as well as allow the top to move easier rocking side to side etc.
Alan Carruth wrote:
I've always felt that a quartered surface glues a little better, but some folks tihnk it's the other way.
Is the glueing issue the only reason that braces are traditionally attached with the grain perpendicular to the soundboard?

Regards

Craig.
Author:  truckjohn [ Tue Mar 17, 2009 9:06 pm ]
Post subject:  Re: upper face brace
X2 on what Al said. I have seen some numbers that indicate Flat sawn is marginally stronger than Quartersawn....

Now, consider that if you took care to get an A1 quality glue joint... and that it will be tucked into the linings... Probably plenty strong.

On splitting stuff out...

There is nothing like sawing out the X... then getting the plane in there and finding a nice grain sworl about 1" above the X intersection.... when the plane grabs it and yanks out a nice large chunk.

Then there is nothing like sawing out the X and Tone Bars.... gluing them down, then finding that the "Easy" tearout free shaving direction is Upwards towards the X rather than downwards from the X.

Good luck

John
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